"The concepts for both cities are in place," explains chair holder Prof Dr Markus Zdrallek. "The aim of the workshop and joint exchange was to explain this, but above all to present a blueprint for other cities and municipalities to plan their own emergency supply," says the energy expert.

The SiSKIN research project (large-scale power outage - options for partial supply of critical infrastructures) paved the way for the concepts. At the centre of the concepts are forward-looking stand-alone grids that have already successfully passed their first tests.

Stand-alone grids are local power grids that are operated independently of the higher-level grid and enable a rapid partial supply in crisis situations. Power plants with black start capability - i.e. those that can be restarted after a power failure without external energy - battery storage and decentralised generators such as combined heat and power plants or renewable energies can be used to restore the power supply in a targeted manner.

In the SiSKIN research project, researchers at the University of Wuppertal developed strategies for grid operators to be able to quickly put sub-grids back into operation in the event of blackouts. Laboratory and field tests confirmed the technical feasibility and showed ways to implement them.

Establishing a reliable power supply

"A key result of the project is detailed island grid planning, which shows how grid operators can operate sub-grids autonomously. It was investigated how a stand-alone grid can be set up and which switching operations are required to ensure a stable and reliable power supply," summarises Prof Zdrallek.

Together with the electricity and gas distribution network operator WSW Netz from Wuppertal, research was also carried out into how such a stand-alone network can be set up on site. The focus here was on the specific conditions of the local electricity grid and the integration of existing generation plants such as waste-to-energy plants, combined heat and power plants and renewable energies.

Another key milestone in the project was a large-scale field test at Energieversorgung Leverkusen (EVL). Here, a real grid section was isolated and re-energised with a black-start-capable generation unit - a waste-to-energy plant.

The test was successful: the power plant was able to start up independently and keep the isolated grid stable while a consumer was switched on. Zdrallek: "These findings show that it is possible to supply critical infrastructure with power in a targeted manner in an emergency and thus minimise the effects of a blackout."

Follow-up project ensures transferability

Building on the results of SiSKIN, the SiSKIN Applied connection project was launched. While SiSKIN investigated feasibility, the focus is now on practical implementation. The main focus here is on the transferability of the developed concept to other networks. The aim is to apply the concept to various network structures.

Further field tests and pilot projects will help to transfer the developed concepts into practice and provide grid operators with concrete solutions. "The long-term goal," says Prof Zdrallek, "is to make cities and supply grids more resilient to large-scale power outages and to sustainably improve security of supply."